This invention relates to sighting devices for firearms and more particularly to rugged lenseless or open sights which are suitable for use under combat conditions for military purposes.
Under adverse conditions of lighting and weather which are frequently encountered in military operations, gun sights which are complex in construction and operation can become severely burdensome to the user. Complex vernier sight adjustment mechanisms are prone to malfunction when dirty. Similarly, gunsights having optical components such as lenses are somewhat fragile and can become broken or fogged by the admittance of moisture, thereby rendering such sighting devices virtually useless. For this reason most gunsights authorized for military usage have traditionally been of the non-optical or open sight type. A fixed front blade sight having a brightened upper bead portion or having a plain square topped post has become almost universally accepted for such usage. Rear sight components have not become as uniform in acceptance, however. Relatively large circular aperture peep sights, V-shaped notches, square shaped notches, U-shaped notches and combinations of these shapes have all been accepted for military usage in conjunction with the usual front blade sight.
A common problem to all such open rear sights has been that of providing the sight with vertical and horizontal movement necessary in order to elevate the muzzle of the piece or translate it from side to side in order to correct for projectile trajectory and windage when a proper sight picture is obtained.
With prior type military open sights, in making correction for projectile trajectory, it has been necessary to have some prior knowledge or estimate of the range to the target. It has also been necessary to have prior knowledge of the trajectory characteristics of the projectile. With the projectile trajectory known and the target range known, it is then possible to elevate the open rear sight by an amount sufficient to raise the muzzle to allow for the fall of the projectile in passing from the piece to the target. It would be desirable to simplify and accelerate the procedure heretofore used for this purpose of making a range estimate and then elevating the rear aperture to correct for projectile trajectory.
Accordingly, it is an object of the invention to provide a simple and fast operating gunsight suitable for military usage which avoids the necessity of making a separate range to target estimation or measurement in its operation.
Another object of the invention is to provide a gunsight rugged enough in construction for military usage which is capable of providing a range estimate to a target.
The above and other objects, features and advantages of the invention are provided in a range finding gunsight. In the gunsight of the present invention, a conventional front blade sight near the muzzle of the piece is used. The rear portion of the sight comprises a rugged baseplate portion which is laterally translatable by means of a conventional worm gear to provide for windage adjustments. An upright sighting member having an elongated oval shaped sighting aperture therein and provided with a target range scale is integrally attached to the baseplate. A slide member comprising an opaque horizontal bar member having a fixed aperture circular peep is provided which is snugly but slideably fitted to the exterior portion of the upright sighting member. Vertical motion of the slide member is controlled by an adjusting screw having a knurled knob on one end thereof and which is rotatably mounted on one side of the upright sighting member. The opposite end of the adjusting screw is provided with a rotatable end mount in the base member.
The area above the horizontal bar member within the elongated oval shaped sighting aperture is increased or decreased in length as the slide member is moved vertically along the upright sighting member and thereby defines a variable length oval shaped sighting aperture. The arrangement is such that when a target whose height is approximately known completely fills the length of the variable length oval sighting aperture, the range to the target may be read from the range scale. Also, if a conventional sight picture is taken at this time (for example, with the front blade filling half the elongated oval aperture), then the trajectory of the projectile in passing from the piece to the target is compensated for in the sense that the projectile will strike someplace on the known sized target.
Other advantages of the invention will be apparent from the detailed description to follow. The invention may best be understood by reference to the detailed description herein when taken in conjunction with the accompanying drawings, in which: